When producing synthetic fibers or filaments and particularly synthetic continuous filaments usable for textiles from heat softened mineral material such as molten glass or the like, it is conventional practice to use a stream feeding container or bushing, normally made of platinum alloy, having a bottom wall with a plurality of orifices through which pass streams of the heat softened mineral material. Suitable apparatus attentuates the streams into continuous fibers or filaments. Further, it has been a practice to fashion the bottom wall of the feeder of the stream feeding container with orificed projections.
Heretofore there has been available only a few practical ways for producing the orificed wall of stream feeding containers and orificed projections that are normally a constituent of such feeders, especially feeders for feeding streams of molten glass. In one practice the orificed wall of the stream feeding container, normally made of a platinum alloy, is fashioned with projections from raised portions that may be built-up on the plate by flame-fusing drops of globules of platinum alloys at spaced regions on the plate. Subsequent coining or chaping of the raised portions provides projections of desired shape. Thereafter, suitable means such as drilling opens a passageway through each of the heretofore solid base plate and projections to provide a passageway opening through the base plate and extending longitudinally of the projections through which heat softened material may flow. Further, it has been another practice to manufacture feeders or tip sections by securing flanged tubular eyelet-like members in registry with openings in a base plate by welding the flanges to the plate.
The prior art methods and apparatus for producing stream feeders are inadequate and slow. When the orificed projections are made by first forming raised portions on a plate, the formation of such raised portions and subsequent passageway formation, e.g. by drilling, is exceedingly slow. Moreover, when the process includes drilling the passageways, the passageways of the individual orificed projections are non-uniform. "Drill drift" contributes significantly to the non-uniformity between orifice projections by making passageways that do not run axially of the projections. Additionally, apparatus tends to lack the accuracy for on center drilling, thereby producing orificed projections having axially extending passageways laterally offset varying amounts. Then too, drills tend to produce passageways having differing passageway surface characteristics, which promotes non-uniformity among individual fibers produced from the stream feeding container.
The deficiencies of the prior art have become more acute under modern filament forming conditions where the size and character of the passageways of the projections have become more critical and the number of orificed projections have often increased to 2,000 or more on feeders used for producing glass filaments. Moreover, uniformity of filament diameter is of considerable competitive concern wherein all filaments, e.g. glass filaments, within a bundle require a high degree of uniformity.
The processes using tubular eyelets, while providing some advance in the art, are severely limited. For example, drilling the holes in the plate into which the tubular members are inserted is an extremely slow process. While such holes may be punched much faster, the fact that the plate will bow due to the stresses set up within the plate inherent in the punching operation requires that the plate be straightened before proceeding with subsequent fabrication operations. Furthermore, the plate will expand across its length and width as the holes are punched thereby distorting the relative location of the holes even more. In addition due to the close spacing of the holes as successive holes are punched the shape of the previously punched holes will change. All of these effects require straightening of the plate and they also require the tubular members be manually inserted or that special equipment be used to locate the true position of the hole before the tubular members can be inserted automatically.